1. Technical Field
Methods for isolation films of semiconductor devices are shown and described.
2. Disclosure of the Related Art
As semiconductor devices become more highly-integrated, semiconductor manufacturing processes become more complicated. Further, there is an urgent need for the development of isolation film technology having good electrical properties at a small area.
Technologies for fabricating isolation films include a shallow trench isolation method. A pad oxide film and a pad nitride film are first sequentially formed on a semiconductor substrate. An isolation mask is then formed on the pad oxide film. If the pad nitride film, the pad oxide film and the semiconductor substrate of a predetermined thickness are etched by means of the etch process using the isolation mask, trenches are formed in the semiconductor substrate. An insulating film for trench burial is formed to bury the trenches, and the top surface of the insulating film is then polished. The pad nitride film and the pad oxide film are then removed.
At this time, a moat is unintentionally created in which the oxide film is located at the interface between the oxide film burying the trenches and the semiconductor substrate, i.e., the interface between an inactive region and an active region of the isolation region is etched into the trenches. This makes a subsequent process difficult and causes the leakage current of the semiconductor substrate.
Accordingly, there is a need for technology that can improve threshold voltage characteristics of cells by avoiding the above-described moat phenomenon that can be generated at the interface between an inactive region and an active region, and that can enhance the reliability of semiconductor devices by securing characteristics of a stabilized transistor.